Multidrug resistant gastrointestinal, fecal bacteria (MRF) are proliferating at a considerable rate to reach and impact downstream food chains, as well as hospital settings. MRFs, including gram-negative Escherichia coli and gram-positive Enterococcus faecium are of prime concern to food safety and public health. While there are several foodborne pathogens originating from animal gut having resistance, MRFs-including Vancomycin Resistant E. faecium (VRE)—remain the leading cause of hospital-acquired infections.
Clonal complex resistant strains (CCs) of Enterococcus faecium, including mainly the multidrug resistant strain, have emerged as a leading cause of nosocomial pathogens, constituting a serious level of threat that has caused almost 10,000 infections and 650 deaths each year in the U.S. Clonal complex 17 (CC17) is now the primary cause of patient urinary tract and bloodstream infections in hospitals and could further lead to endocarditis and death primarily in immunocompromised populations, along with serious complications primarily in patients with long stay in hospitals.
Conjointly in this pathogenic spread, Escherichia coli is implicated in millions of extra-intestinal infections, resulting in more than 100,000 cases of sepsis and 40,000 sepsis-associated deaths. Moreover, the enormous intrinsic capability and phenotypic elasticity of the MRF strains—mainly E. faecium—enable them to acquire other genes from the environment, mutate continuously, and transfer genes to other pathogens, including primarily Salmonella and Campylobacter genera found in food animals. Although some strains of E. faecium are used in the food industry and are also known for their probiotic attributes, the tremendous ability of some strains to acquire resistance would be a major bottleneck. It is also quite possible that resistant MRFs from food form a niche in a human's gastrointestinal tract, leading to a reservoir of resistance and consequently jeopardizing the lives of the most immunocompromised populations.
Despite the increasing threat of mutating MRFs, many strains of E. faecium are also lactic acid bacteria and are known for their probiotic attributes. They have been extensively added in food for their fermentative ability and health benefits. It has been shown that rabbits in animal husbandries that were given water containing E. faecium as a probiotic had higher average weight gains as well as a healthier natural intestinal flora. While E. faecium helps prevent antibiotic-associated diarrhea, enhance the immune system, and lower the cholesterol level, other strains are used for their food safety attributes in limiting zoonotic pathogens from food animals through bacteriocin production. Despite their probiotic attributes, the considerable ability of some E. faecium strains to mutate in multiple types of environments has made the use of E. faecium as a fermentative strain questionable. Furthermore, the continuous use of the traditional antibiotics has led to the induction of “Super Bugs” that are unresponsive to a wide range of antibiotics. Some strains of multidrug resistant fecal bacterial—primarily Enterococcus—has exhibited the ability to develop resistance to most, if not all, drugs used against them.
A substantial review on the antibacterial properties of bacteriocins has been implemented by Fisher and Phillips [Fisher, K et al. (2009). The ecology, epidemiology and virulence of Enterococcus. Microbiol. 155:1749-1757]. However, the tremendous ability of some strains to acquire virulence genes from other strains and convert into pathogenic strains would hinder the beneficial attributes of E. faecium. This is increasingly more problematic due to the considerable ability of E. faecium to mutate and acquire virulent genes in multiple types of environment.
In addition to the proliferation of nosocomial and food animal-related MRFs, the presence of multidrug resistant bacteria, including recently recognized alternative fecal indicator Pseudomonas aeruginosa[Liang L, et al. (2015). Alternative fecal indicators and their empirical relationships with enteric viruses, Salmonella enterica, and Pseudomonas aeruginosa in surface waters of a tropical urban catchment. Appl Environ Microbiol 81:850-860.] has been elucidated in municipal wastewaters used for algae cultivation [Limayem A, et al. (2017). Prokaryotic community profiling of local algae wastewaters using advanced 16S rRNA gene sequencing. Environ Sci Pollut Res. https://doi.org/10.1007/s11356-017-0078-z; Limayem A, et al. (2016). Molecular identification and nanoremediation of microbial contaminants in algal systems using untreated wastewater. J. Environ. Sci. Health., Part B 51(12): 868-872].
Algae biomass-fed wastewater is an emerging cost-effective medium with a multiplicity of uses including but not limited to food in aquaculture, remediation in wastewater treatments, algal lipid production and algal bioenergy manufacture. In regards to bioenergy manufacture specifically, algae biomass-fed wastewaters are increasingly spurring interest among researchers after escalating concerns of climate change due to its ability to act as a CO2 sink, generating a higher yield per acre of biofuel than other natural sources [Von Sivers M., Zacchi G. (1996). Ethanol from lignocellulosics: a review of the economy. Bioresour Technol. 56:131-140.; Goldemberg J. (2007). Ethanol for a sustainable energy future. 315: 808e10.].
Wastewaters provide delivery of nutrients such as phosphorus and nitrogen but also can host some resistant bacterial strains, which are of prime concern in algae production that is performed under non-aseptic conditions. The algal crop is susceptible to grazing from multidrug resistant Pseudomonas aeruginosa and other alternative microorganisms, which would have infectious properties, creating unsafe work conditions. Therefore, a novel natural antibiotic is of dire need for this valuable “green” industry.
Accordingly, what is needed is an effective intervention mechanism/therapy for mitigating or reducing multi-drug resistant bacterial pathogens found in food animals, humans, and the respective environment. As applied to algae biomass-fed wastewaters, what is needed is an integrated system approach to employ molecular and systemic methods to trace multidrug resistant bacterial flora from the source, which requires a complete screening of the predominant prokaryotic groups in algal systems to ensure an efficient nanoremediation. However, in view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the field of this invention how the shortcomings of the prior art could be overcome.
While certain aspects of conventional technologies have been discussed to facilitate disclosure of the invention, Applicants in no way disclaim these technical aspects, and it is contemplated that the claimed invention may encompass one or more of the conventional technical aspects discussed herein.
The present invention may address one or more of the problems and deficiencies of the prior art discussed above. However, it is contemplated that the invention may prove useful in addressing other problems and deficiencies in a number of technical areas. Therefore, the claimed invention should not necessarily be construed as limited to addressing any of the particular problems or deficiencies discussed herein.
In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of common general knowledge, or otherwise constitutes prior art under the applicable statutory provisions; or is known to be relevant to an attempt to solve any problem with which this specification is concerned.